This application seeks to develop scanning ion conductance microscopy (SICM) as a dynamic tool for the study of cell-cell contacts, gaps and spaces. Our long-term goal is to understand transport through tight junctions at the nanometer scale. The objective of this application is to obtain quantitative and qualitative measurements of transport through tight junctions at the level of tens of nanometers using in vitro models. The central hypothesis of the application is that scanning ion conductance microscopy can be used to image transport through individual tight junctions at resolutions. The rationale for the proposed research is that using SICM both spatial and temporal response can be measured, allowing analysis of tight junctions. Our study has two specific aims. The first specific aim is to establish capabilities of SICM for imaging of transport through synthetic mimics of tight junctions. The second specific aim is to establish SICM for qualitatively and quantitatively examining the role of tight junctions in transport at the nanometer scale using in vitro models comprised cultured epithelial cells. The proposed work is innovative because it uses a new platform to collect both spatial and temporal information tight junction transport. The expected outcomes are to create a tool that can be used to study transport through tight junctions at the nanometer scale. The ability to monitor transport at these levels will provide new opportunities to study biological models. PUBLIC HEALTH RELEVANCE: This application describes a new way to characterize tight junctions that regulate transport across the interface of epithelial tissues. This study will develop a tool that can impact research in disease related to tight junctions (e.g. cancer, cystic fibrosis) and drug delivery across relatively impermeable biological interfaces (e.g. the blood brain barrier).